After seeing how short the duration is on the cam, I’m not surprised by the shape of the TQ curve.
The Hp curve is still climbing slightly, and at least on the sheet you posted, there no obvious signs of a problem.
With Hyd lifters the loss of control point is often like a switch………might be good at 5200, and in the crapper at 5300.
I usually go high enough to know where the end is………then keep it under that point for the remainder of the testing.
You may have done that prior to the pull you posted.
I'll pm you a google link to pull video where it's audible right at the top end.
I guess this is where a spintron service comes into play. There is a local guy that test distributors so I may do that just to rule that out as well.
